diff --git a/PROTOCOL.md b/PROTOCOL.md
index d526706..2123625 100644
--- a/PROTOCOL.md
+++ b/PROTOCOL.md
@@ -96,7 +96,7 @@ At this point, the new key/session becomes active.
 ### ecdhe
 
 This is the ECDHE key exchange.  This does an ephemeral key exchange
-w/ a known static key.  It follows a protocol similar to the KK
+w/ a known static keys.  It follows a protocol similar to the KK
 [handshake pattern](https://noiseprotocol.org/noise.html#interactive-handshake-patterns-fundamental)
 of Noise.  For reference, it is:
 ```
@@ -111,6 +111,10 @@ KK:
 It requires that both sides know the public key of the other side (and
 obviously their own).
 
+As the strobe code includes an implementation of X25519 (ECDH over
+Curve25519), that is used.  This means the various public keys are all
+32 bytes in length.
+
 Both start out:
 ```
 meta-AD('com.funkthat.lora.irrigation.ecdhe.v0.0.1')